Clustered filesystem with data volume snapshot

• US 9,792,296 B2
• Filed: 10/01/2014
• Issued: 10/17/2017
• Est. Priority Date: 06/05/2001
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Inventors: Beck, Kenneth
• Primary Examiner(s): Alam, Hosain
• Assistant Examiner(s): ALLEN, NICHOLAS E
• Application Number:
  US14/504,368
• Publication Number:
  US 20150019492A1
• Time in Patent Office: 1,112 Days
• Field of Search: 707204, 707639
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 16/128 Details of file system snapshots on the file-level, e.g. snapshot creation, administration, deletion use of snapshots for error detection or correction G06F11/14, G06F11/16
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/564 Enhancement of application control based on intercepted application data
• CPC Class Codes: H04L 67/566 Grouping or aggregating service requests, e.g. for unified processing
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/966 Distributed

Abstract

A computer system with read/write access to storage devices creates a snapshot of a data volume at a point in time while continuing to accept access requests to the mirrored data volume by copying before making changes to the base data volume. Multiple snapshots may be made of the same data volume at different points in time. Only data that is not stored in a previous snapshot volume or in the base data volume are stored in the most recent snapshot volume.

Claims

1. A method for maintaining a copy of a data volume for a computer system for at least one point in time, the method comprising:

receiving a read request for at least a portion of at least one of one or more snapshots of a base volume from a requestor;

identifying that the read request to the at least one or more snapshots includes a region that has changed since a first snapshot was initiated, and includes a region that has not changed since the first snapshot was initiated, wherein the identification that the at least one or more snapshots includes the region that has changed since the first snapshot was initiated is identified by accessing at least one region modified map of a plurality of modified region maps, and each of the plurality of modified region maps are associated with a different snapshot of the one or more snapshots;

reading data from the region that has changed since the first snapshot was initiated from the first snapshot;

reading data from the region that has not changed from the base volume;

transmitting the data from the region that has changed since the first snapshot was initiated and the data from the region that has not changed to the requestor;

identifying that a portion of data associated with a file has been deleted; and

copying the deleted portion of the data associated with the file from the base volume to the first snapshot.

2. The method of claim 1, wherein the region modified map includes a bit representing each region of the base volume, and the bit indicates whether data in the region has changed.

3. The method of claim 1, wherein the at least one of the one or more snapshots are stored in a repository, and the repository is implemented as a filesystem within which space is allocated in blocks.

4. The method of claim 3, wherein at least one of the blocks are read when identifying that the region has changed.

5. The method of claim 1, further comprising:

identifying that additional memory is required to maintain the first snapshot; and

dynamically allocating additional memory to the first snapshot after identifying that the additional memory is required to maintain the first snapshot.

6. The method of claim 1, further comprising:

identifying that the read request also includes a region that has changed since a second snapshot was initiated;

reading data from the second snapshot that has changed since the second snapshot was initiated; and

transmitting the data from the region that has changed since the second snapshot was initiated to the requestor.

7. A non-transitory computer readable storage medium having embodied thereon a program executable by a processor to perform a method for maintaining a copy of a data volume for a computer system for at least one point in time, the method comprising:

receiving a read request for at least a portion of at least one of one or more snapshots of a base volume from a requestor, wherein the identification that the at least one or more snapshots includes the region that has changed since the first snapshot was initiated is identified by accessing at least one region modified map of a plurality of modified region maps, and each of the plurality of modified region maps are associated with a different snapshot of the one or more snapshots;

identifying that the read request to the at least one or more snapshots includes a region that has changed since a first snapshot was initiated, and includes a region that has not changed since the first snapshot was initiated;

reading data from the region that has changed since the first snapshot was initiated from the first snapshot;

reading data from the region that has not changed from the base volume;

transmitting the data from the region that has changed since the first snapshot was initiated and the data from the region that has not changed to the requestor;

identifying that a portion of data associated with a file has been deleted; and

copying the deleted portion of the data associated with the file from the base volume to the first snapshot.

8. The non-transitory computer readable storage medium of claim 7, wherein the region modified map includes a bit representing each region of the base volume, and the bit indicates whether data in the region has changed.

9. The non-transitory computer readable storage medium of claim 7, wherein the at least one of the one or more snapshots are stored in a repository, and the repository is implemented as a filesystem within which space is allocated in blocks.

10. The non-transitory computer readable storage medium of claim 9, wherein at least one of the blocks are read when determining identifying that the region has changed.

11. The non-transitory computer readable storage medium of claim 7, further comprising:

identifying that additional memory is required to maintain the first snapshot; and

dynamically allocating additional memory to the first snapshot after determining identifying that the additional memory is required to maintain the first snapshot.

12. The non-transitory computer readable storage medium of claim 7, the program further executable to:

identify that the read request also includes a region that has changed since a second snapshot was initiated;

read data from the second snapshot that has changed since the second snapshot was initiated; and

transmit the data from the region that has changed since the second snapshot was initiated to the requestor.

13. A system for maintaining a copy of a data volume for a computer system for at least one point in time, the system comprising:

a memory;

one or more processors, wherein the one or more processors executes instructions out of the memory to;

receive a read request for at least a portion of at least one of one or more snapshots of a base volume from a requestor over a computer network,

identify that the read request to the at least one or more snapshots includes a region that has changed since a first snapshot was initiated, and includes a region that has not changed since the first snapshot was initiated,

read data from the region that has changed since the first snapshot was initiated from the first snapshot, and

read data from the region that has not changed from the base volume; and

a communications interface communicatively coupled to the computer network and that transmits the data from the region that has changed since the first snapshot was initiated and the data from the region that has not changed to the requestor over the computer network, wherein a portion of data associated with a file has been deleted is identified, and the deleted portion of the data associated with the file is copied from the base volume to the first snapshot.

14. The system of claim 13, wherein the region modified map includes a bit representing each region of the base volume, and the bit indicates whether data in the region has changed.

15. The system of claim 13, wherein the at least one of the one or more snapshots are stored in a repository, and the repository is implemented as a filesystem within which space is allocated in blocks.

16. The system of claim 15, wherein at least one of the blocks are read when identifying that the region has changed.

17. The system of claim 13, wherein the processor:

identifies that the read request also includes a region that has changed since a second snapshot was initiated;

reads data from the second snapshot that has changed since the second snapshot was initiated; and

transmits the data from the region that has changed since the second snapshot was initiated to the requestor.